The present invention relates to a plasma display panel (PDP), and, more particularly, to a PDP improved with rightness.
Plasma display panel (hereinafter referred as to PDP) is a flat board display device using the effect of vacuum ultraviolet rays that excites red (R), green (G) and blue (B) fluorescent substances and subsequently generates visible rays. The vacuum ultraviolet rays are emitted from plasma generated during the discharge out as, such as Ne or Xe, filled in a space between the front plate and the rear plate.
PDP is divided into a direct current (DC) type and an alternating current (AC) type. In a DC-type PDP, an electrode used to supply voltage from outside to form plasma is exposed directly to the plasma and the conduction current flows directly through the electrode. It has an advantage that the structure is very simple, but has a disadvantage that it should equip external resistance to limit the current because the electrode is exposed in the discharge space.
In an AC-type PDP, an electrode is not exposed directly but covered with a dielectric substance, so displacement current flows. Since the electrode is covered with a dielectric substance, electric current can be limited naturally. Also, because the electrode can be protected from ion impact during the discharge, the AC-type PDP has a longer lifetime compared to the DC-type PDP.
The AC-type PDP can be classified into an opposite discharge type and a surface discharge type. The opposite discharge type has a problem that the life span is short due to degradation of fluorescent substances caused by the ion impact. In the surface discharge type, on the other hand, the discharge is collected in a panel opposite to the fluorescent substances in order to minimize the degradation of fluorescent substances and thus overcome the structural disadvantage of the opposite discharge type. Nowadays, most PDP devices adopt the surface discharge type.
Meanwhile, among various flat display devices, the PDP can easily realize a wider and thinner screen. Because of this advantage, the PDP in today has broad applications by being increasingly used for a real time display screen in stock trading markets, a display screen for a conference and a wall frame television with a wide screen.
FIG. 1 is a diagram showing a layout of a surface discharging AC type PDP using three electrodes. Particularly, the diagram in FIG. 1 shows an array of the electrodes.
Referring to FIG. 1, the surface discharging AC type PDP includes a front substrate 11 and a rear substrate 11A. An X electrode 12 and a Y electrode 13 are formed in a row direction. An address electrode 14 is formed in a direction where the X electrode 12 and the Y electrode 13 cross to each other.
Also, a cell 15 is constructed on a point where each of the electrodes is crossing. Especially, the X electrode 12 is a scan electrode used for scanning a screen. The Y electrode 13 is a sustain electrode used for sustaining a discharging state. The address electrode 14 is used for inputting data.
The address electrode 14 formed in each cell is supplied with an address voltage by being connected to an address driver. The X electrode 12 is connected to an x electrode driver and supplied with a scan voltage. The Y electrode 13 is supplied with a sustain voltage by being connected to a Y electrode driver.
The X and Y electrodes and the address electrode are constructed and a matrix form.
FIG. 2A is a cross-sectional view of the surface discharging AC type PDP with the three electrodes in accordance with a preferred embodiment of a prior art.
Referring to FIG. 2A, the front panel includes a front electrode having a front substrate 21, a pair of transparent electrodes being positioned with a predetermined distance from the front substrate 21, a pair of bus electrodes being formed on top of each transparent electrode 22, a transparent dielectric layer 23 limiting discharge current-by being formed on the front electrode, a protection layer 24 for protecting the transparent dielectric layer 23 being formed beneath the transparent dielectric layer 23. The front electrode constitutes X and Y electrodes shown in FIG. 1. For example, one transparent electrode 22 and the bus electrode 22A constitute the X electrode while the other transparent electrode 22 and the bus electrode 22A constitute the Y electrode.
A rear panel includes a rear substrate 21A, an address electrode 25 formed on the rear substrate 21A in a direction of acrossing the front electrode, a white dielectric layer 26 for protecting the address electrode 25 and simultaneously reflecting visible rays emitted from a discharging space 29 by being formed entirely on the rear substrate 21A including the address electrode 25, a barrier rib 27 for preventing the cross-talk phenomenon occurring between cells neighboring the address electrodes 25 being formed in a stripe shape and a fluorescent substance 28 emitting visible rays by being formed on the white dielectric layer 26 and at lateral sides of the barrier rib 27.
The discharging space 29 where inert gas is added and sealed is formed in a space provided when the front panel and the rear panel are connected.
Referentially, rig. 2A shows the front substrate 21 rotated in 90xc2x0 for a conventional purpose. Discharge cells are isolated through the barrier rib 27 in a stripe shape.
The following will describe procedures until the discharge cells luminesce based on the above structure of the PDP.
Firstly, in connection with the discharge cell to be lighted, a predetermined voltage is supplied to a space between the Y electrode and the address electrode 25 so to induce discharge between the two electrodes. Due to this type of discharge, a positively ionized ion and an electron are stored into surfaces of the fluorescent substance 28 and the protection layer 24 as wall-charges.
In the discharge cell stored with the wall-charges, a voltage is supplied to the X electrode. Once the voltage is supplied, then, there occurs another discharge between the Y electrode and the X electrode.
Afterwards, the discharge occurs repeatedly due to the X and Y electrodes as they are supplied with an alternate electric field. This repeated discharge is called sustain discharge. Ultraviolet rays emitted by the sustain discharge are changed into visible rays as the ultraviolet rays excite the fluorescent substance 28. The visible rays are then transmitted through the front substrate 21 and emitted to outside.
As described in the above, a conventional PDP has the barrier rib 27 for preventing erroneous discharge between left and right cells.
Generally, the barrier rib 27 has a stripe shape being placed in a parallel direction to the address electrode 25. The conventional PDP, however, does not have a barrier rib for preventing charge movements between upper and lower calls. Therefore, a distance between the bus electrodes is set to be sufficiently large to prevent the charge movements between the upper and lower cells, thereby preventing reciprocally erroneous discharge between the cells.
The barrier rip having the strip shape is compelled to isolate each cell into two regions. That is, the two, regions are isolated into a section including a transparent electrode causing ultraviolet rays emitted due to the main discharge to react with a fluorescent substance so to emit visible rays and a black stripe region for preventing occurrences of the discharge further to prevent emission of visible rays. The region including the transparent electrode is responsible for realizing an image by emitting the visible rays.
A ratio of emitting visible rays per cell increases in proportion to an increase in an area of the discharge region in one cell. Therefore, the luminescence efficiency is also improved.
However, in the conventional PDP having the stripe shape and the barrier rib, if the area of the region for the discharge increases, there easily occurs erroneous discharge because the distance between the electrodes of the upper and the lower cells decreases. Actually, in a 40-inch VGA PDP having the barrier rib with the stripe shape, the area of the discharge region in one cell occupies only about 50%. This fact becomes a cause for decreasing the luminescence efficiency due to a decreased ratio of an actual area of the luminescence region.
Also, in case of adopting the barrier rib with the stripe shape, it is an ease of exhausting due to sufficiently attained paths for exhausting. On the other hand, ultraviolet rays emitted due to the discharge and visible rays are able to easily transmit to neighboring cells, and thus, the ultraviolet rays are dissipated. This dissipation of the ultraviolet rays further becomes a factor for decreasing brightness. Furthermore, there may occur erroneous discharge and cross-talk phenomena due to interference of charged particles of the neighboring cells. Hence, a lattice type barrier rib structure is proposed to solve the above listed problems.
FIG. 2B is a diagram showing the lattice type barrier rib proposed to solve the problems,when using the stripe type barrier rib (referred to FIGS. 4 and 5 of the Korean Patent No. 10-351846).
The lattice type barrier rib includes an array of cells, each cell being surrounded with the barrier rib so as to block the ultraviolet rays emitted due to the discharge and the visible rays from being transmitted to neighboring cells. As a result of this specific structure, it is possible to prevent occurrences of erroneous discharge and the cross-talk phenomenon due to charged particles between the neighboring cells.
Also, a dielectric layer is formed with a groove for flowing exhaust gas freely.
However, the conventional PDP with the lattice type barrier rib has an array of cells, each being blocked in all directions due to the barrier rib. Thus, this fact results in a limitation in a free flow of the exhaust gas and a complex process due to an additional process added to form the groove.
Meanwhile, the front substrate of the conventional PDP uses indium thin oxide (ITO) as a transparent electrode in order to allow visible rays to be transmitted. However, since the ITO has high electric resistance, a bus electrode using a material having a good electric conductivity such as an Ag layer and a stacked layer of Crxe2x80x94Cuxe2x80x94Cr is formed on top of the ITO to complement the high electric resistance of the ITO.
However, the formation of the ITO electrode has a problem of increasing costs due to increases in expenses for materials and the number of processes.
It is, therefore, an object of the present invention to provide a plasma display panel (PDP) capable of preventing increases of expenses for materials and the number of processes based on a structure of the PDP including a front electrode which has a transparent electrode and a bus electrode, of improving an exhausting function and of preventing occurrences of erroneous discharge and the cross-talk phenomenon between neighboring cells.
In accordance with an aspect of the present invention, there is provided a plasma display panel (PDP), comprising: a vertical barrier rib and a horizontal barrier rib, wherein the vertical barrier rib and the horizontal barrier rib form a hexagonal shape to encompass discharge cell region in all directions; a connection barrier rib connecting the vertical barrier rib to the horizontal barrier rib, wherein the connection barrier rib have a groove at a central portion thereof so that a length of the horizontal barrier rib is shorter than a distance between the vertical barrier ribs; and a gas-passing path formed above a top surface of the horizontal barrier rib of which height is lowered with respect to a surface of the vertical barrier rib, wherein the horizontal barrier rib prevents erroneous discharge in a vertical direction, the vertical barrier rib prevents erroneous discharge in a horizontal direction and the vertical barrier rib, the horizontal barrier rib and the connection barrier rib are connected to each other to provide a hexagonal discharge cell region.
In accordance with another aspect of the present invention, there is also provided a surface discharging alternating current (AC) type plasma display panel (PDP) with three electrodes, comprising: a pair of front electrodes; and an address electrode, wherein each front electrode of a unit discharge device, including: a main electrode and a terminal electrode being paired by having a uniform distance in a direction of making a perpendicular cross at a center of the barrier rib; and a branch electrode connecting the main electrode to the terminal electrode by being formed in a parallel direction to the barrier rib at the center of the barrier rib, wherein each line width of the main electrode, the terminal electrode and the branch electrode is different, and the main electrode, the terminal electrode and the branch electrode are bus electrodes without having a transparent electrode.
In accordance with still another aspect of the present invention, there is also provided a plasma display panel, comprising a unit discharge device, wherein the unit discharge device includes: a front substrate and a rear substrate; a pair of bus electrodes in a trapezoidal shape by being formed in a first direction on the front substrate; an address electrode formed on the rear substrate in a second direction of making a cross with the pair of the bus electrodes; a dielectric layer forming on the rear substrate including the address electrode; a hexagonal barrier rib encompassing a discharge cell region defined by the pair of the bus electrodes and the address electrode and providing a gas-passing path due to a fact that a height of one side of the barrier rib is lower than that of the other side of the barrier rib; and a fluorescent substance coated on an entire area of the discharge cell region encompassed by the hexagonal barrier rib.